Remarks by Sens. Marco Rubio and Rand Paul to their party's conservative core on Thursday were a sneak peek at the roster of possible 2016 Republican presidential candidates and hints at the direction of a party in the midst of a makeover.

In both cases, political experts say, the GOP has a lot of work to do.

"Part of it is trying to find the next generation of leaders. But because in some ways they are so inexperienced and untested, it is evidence that Republicans have a very thin team right now," said Julian Zelizer, a Princeton University historian and CNN contributor. "They are relying on voices and politicians that are not tested in a national arena."

Rubio, the son of Cuban immigrants and Paul, the son of libertarian maverick former Rep. Ron Paul, R-Texas, made several allusions to their youthful energy when they walked into main ballroom at the Conservative Political Action Conference.

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But their value as speakers and burgeoning leaders within their party go beyond their youth, Zelizer said.

"Rubio represents an effort to broaden their base and bring in immigrants. Paul represents a kind of libertarian, individualistic and anti-government ethos," Zelizer said.

"They are searching for new voices and new talent. (Rubio and Paul) are up-and-comers and they represent a part of the party that many people feel has been lost in recent decades," he added.

An upcoming, internal report by the Republican National Committee is expected to highlight the need to bring in more of these types of voices as the party continues to regroup in anticipation of the 2014 midterm and 2016 presidential elections.

The report will also stress the need for outreach to specific demographic groups in hopes of identifying more effective ways to attract minority and younger voters.

The appeal to youth was on display on Thursday at the CPAC event outside Washington.

Rubio of Florida, who entered and exited the room to the pop hit "Beautiful" by the boy band One Direction, underscored the need to reduce student loan debt.

Paul of Kentucky made several references to the challenges faced by college graduates looking for work in a still-tough economy overseen by the Obama administration.

"The Facebook generation can detect falseness and hypocrisy a mile away. They are the core of the 'leave me alone' coalition. They doubt that Social Security will be there for them," Paul said. "They worry about jobs and money, rent and student loans. They want leaders that won't feed them a line of crap or sell them short. They aren't afraid of individual liberty."

Both ticked off what they see as benefits of conservatism and the need to safeguard American values.

"Just because I believe states should have the right to define marriage in the traditional way does not make me a bigot," Rubio said. "The people who are actually closed-minded in our society are the ones who love to preach about climate science and refuse to believe the science that life begins at conception."

In many ways, Rubio's speech took a cue from his response on behalf of Republicans to President Barack Obama's State of the Union address. Rubio reiterated why he feels conservatism and limited government are good for the middle class.

He offered no new policy rollouts and while immigration reform wasn't the focus of his speech, he did touch on how he feels being conservative means being pro-legal immigration.

Meanwhile, sources familiar with Paul's remarks said he saw his appearance as an opportunity to establish himself as a mainstream Republican leader following his nearly 13-hour filibuster of John Brennan's nomination as CIA director last week over the Obama administration's policy of targeting terror suspects with drones.

His remarks also sought to touch on various brands of conservatism as he discussed the future of the Republican Party and how to talk about such issues as immigration reform and school choice in a way that unites the GOP.

That effort should focus less on luminaries and more on the people listening to them, Patrick Millsaps, former chief of staff for Newt Gingrich's 2012 presidential campaign, told CNN on Thursday.

"I think the GOP and members of my party, the conservatives, need to be more concerned right now about not who's standing behind the podium, but the people in the seats," Millsaps said. "Those are the people that are very interested in ideas and they are the people that are going to get people elected."